High temperature resistant textile fiber finish composition



United W States Patent Office 3,544,462 Patented Dec. 1, 1970 US. Cl.252-86 1 Claim ABSTRACT OF THE DISCLOSURE A heat-stable finishcomposition for synthetic fibers which comprises (1) a major portionofan alkali metal salt of a phosphate ester where the alcohol portion ofthe ester has from 6 to carbon atoms, and (2) a minor portion of a weakacid such as boric acid. These finishes are applied to the fibers asdilute aqueous solutions.

The development of synthetic fibers having high heatstability and theincreased speed of processing have resulted. in high temperatureoperations in order to give the fibers adequate temperature-timeexposure. The temperatures of draw rolls, drying ovens and texturinggases has been increased to higher than 300 C. The upper limit ofoxidative and thermal stability of conventional finishes has beenreached and new materials or better stabilizers for old materials areneeded.

Mineral oils and waxes; esters of fatty acids, dicarboxylic acids, orphosphoric acid, and certain alkylene oxide polymers and polyglycolethers; have been used for lubricating both natural and syntheticfibers. Some of these also impart antistatic properties to the fibers.Finishes based on low molecular weight compounds are usually toovolatile and are largely lost from the fiber and condense on walls ofdryers and other cool surfaces and sometimes drip onto the fiberscausing discoloration. Some of these finishes are solvents which removepaints and lacquers from the equipment. Finally, any of the thermallyunstable finishes may smoke and fume obnoxiously. Satisfactory finishesshould not hamper the carding and spinning of the fiber into yarns. Somefinishes cause fibers to stick to rolls and cause roll wraps.

The present invention provides fiber finishes which are stable to thehigh temperatures required in high speed processing and which impartstatic resistance and lubrication to the fiber.

These results are achieved in the present invention by applying tosynthetic fibers such as polyamides, polyesters or polyacrylics a finishmade by combining an alkali metal salt of a phosphate ester with anon-volatile weak acid or salt of a weak acid. The esters of phosphoricacid are made from alcohols of 6 to 10 carbon atoms. A preferred esteris the dioctyl phosphate. This is used preferably in the form of itssodium or potassium salt.

The acid may be boric acid, polyacrylic, polymethacrylic or other weakacids such as polycrotonic acid, polyitaconic acid or long-chain fattyacids (e.g. about 16 to 20 carbon atoms) or salts of the fatty acids.The purpose of the acid is to solubilize the alkali salt of thephosphoric ester.

The phosphate ester is generally present in amounts of about to parts byweight and the weak acid is generally present in amounts of about 25 to10 parts by weight. The finish is applied to the fiber as an aqueoussolution containing about one to twenty percent of the finishcomposition. The dry fibers generally have less than one percent byweight of the finish based on the fiber weight after the finish dries onthe fiber. Commonly the finish on the fiber will run about 0.2 to 0.5percent by weight.

The phosphate ester provides both lubrication and antistatic effects. Ifthe chain length of the alkyl group is too long, the antistatic effectis poor. If the chain length is too short, then the lubricant action ispoor. A dial-kyl ester with alkyl chains of about 8 carbon atoms givesgood antistatic protection as well as good lubrication. The alkyl groupsneed not be the same length and a mixture of C and C alcohols or C C andC alcohols can be used.

The following test methods have been used for testing finishes for usein this invention. A sample of the finish is placed in the sample cellresting on the hot plate. A thermometer or a thermocouple is inserted inthe sample cell.

In carrying out the test, the sample is heated at the rate of increaseof 5 C. per minute. The temperature at which the sample first begins tosmoke is recorded as the smoke point. The smoke density of 200 C. isestimated as light, medium, or heavy and recorded as the smoke densityat 200 C.

Another test used to determine a good finish is the thin filmoxidation-evaporation test which measures the tendency of a finish tobuild up on hot areas of the equipment. It is carried out by weighingout -02 gram of the finish in an aluminum cup, heating for 16 hours at200 C., determining the percent residue, and noting the appearance ofthe residue. A large hot plate (30.5 x 30.5 cm.) 12 x 12 inches,protected from drafts or a mechanical convection oven are the preferredmeans of heating. The residue may be negligible or massive, transparentand colorless or cloudy and dark. Many finishes leave an undesirablevarnish-like residue.

Finishes suitable as antistats and lubricants, and stable attemperatures of 200 C. and higher are not common because if they aregood antistats, they are usually of high molecular weight and thus leaveheavy dark residues and if of low molecular weight, they are toovolatile.

Obviously, the chemical structure also affects the properties offinishes. A large number of materials tested failed in one requirementor the other. Some failed because the finish was a solvent for paintsand lacquers.

It is therefore surprising that a finish was found that wassatisfactorily free from all of these objections. The following exampleswill show the results of tests with finishes of this invention and alsoresults vw'th materials not meeting the requirements of this invention.

EXAMPLE 1 A nylon yarn of denier and having 68 filaments is spun frompoly(hexamethylene adipamide) melt containing 0.5% TiO and drawn to a3.2 ratio. This yarn is finished by passing it over a rotating rollwhich'is partly immersed in a bath of the following composition:

EXAMPLE3 V The following finishing compositions are prepared withoutwater which would be used if the finishes were Parts Potassium salt ofdioctyl phosphate 16 P P to fibers Boric acid I 4 5 Fmlsh 1: Parts Water80 Potasslum salt of dioctyl phosphate 80 Boric acid 20 The yarn takesup about 30 parts of the finish for 100 Fmlsh 2: v parts yarn so thatafter drying, the yarn has 0.3% finish. Potassmn} Salt of dloctylPhosphate 90 The yarn is dried by passing through an oven at 250 C. 0Polyacryhc acld (Acrysol A-l manufectured'by and-then bulked by passingthrough a steam jet as taught Rohm & Haas by U.S. Pat. 3,005,251 toHallden. Bulking is accom- Fmlsh 3: plished with 1.9 lbs. ,0.86kilogram) per hour of steam Potassfum Salt of dloctyl Phosphate 80 froma steam source at 60 pounds per square inch (4.2 Potassmm oleatekilograms per sq. cm.) at a temperature of 320 C. 15 Fmlsh 4: I

No objectionable fuming or smoking occurs during Potasslum salt ofdloctyl Phosphate 75 the drying or bulking and no harmful deposits buildup Potasslum oleate on the equipment. The yarn remains free of staticafter The smoke point, the smoke density at 200 C. and the finish isapplied and is sufficiently lubricated to process th thi fil propertiesare d i d b h d d with low running friction. When used as a filling yarn20 scribed above. The results are shown in Table 1 below. in weaving, itdoes not dissolve the varnish from the A conventional mineral oil finishis included for combobbins. parison.

TABLE 1 Conventional mineral Finish 1 Finish 2 Finish 3 Finish 4 fini ll Smoke point C 185 195 200 199 120 Smoke density at 200 C Thin filmtest, percent residue- 41 50 54 59 9. 6 Appearance of residue W Light.Heavy.

3 Deliquescent [rlable light brown foam. 4 Deliquescent friable browngranular solid. 5 Dark brown varnish.

EXAMPLE 2 A fiber is spun from a polymer of hydroxypivalic acid by themethod of Example 4 of US. Patent 2,658,- 055 of Alderson. The fiber inthe form of continuous filament is treated with a solution of thefollowing composition by passing the filaments over a rotating rollpartly immersed in the solution:

Parts Potassium salt of dioctyl phosphate 0.75 Potassium oleate 0.25

Water 99.00

What is claimed is:

1. A high temperature resistant textile fiber finish composition whichconsists essentially of about to parts by weight of an alkali metal saltof a phosphate ester prepared from an alkyl alcohol having 6 to 10carbon atoms and about 25 to 10 parts by weight of boric acid.

References Cited UNITED STATES PATENTS 1,914,331 6/1933 Nuesslein et a].252-8.6X 2,025,435 12/1935 Bou Huys 2528.8X 2,289,127 7/1942 Koch2528.8X 3,341,451 9/11967 Dziuba et al. 252-8.6 3,377,181 4/ 196 8Kamijo et a1. 252--8.6

I HERBERT B. GUYNN, Primary Examiner us. 01. X.R. 117-1395

